(1) Field of the Invention
This invention relates to a solenoid valve-equipped expansion valve in which a solenoid valve and an expansion valve are integrated with each other, and more particularly to a solenoid valve-equipped expansion valve used in a rear-side circuit of an automotive air-conditioning system which is capable of air-conditioning a front side and a rear side of a vehicle compartment, independently of each other.
(2) Description of the Related Art
Conventionally, as an automotive air-conditioning system, a refrigeration cycle is used in which a front evaporator and an expansion valve associated therewith, and a rear evaporator and an expansion valve associated therewith, are arranged in parallel with each other, so as to make it possible to perform air conditioning control of a front side of a vehicle compartment and that of a rear side of the same independently of each other.
When the front-side refrigeration cycle is being used, the rear-side refrigeration cycle is not necessarily used. Therefore, a solenoid valve serving as a stop valve is provided in a rear-side circuit, and when the rear-side refrigeration cycle is not being used, refrigerant is inhibited from flowing.
In view of installation spaces and costs for installing the stop valve and the expansion valve for the above use, a solenoid valve-equipped expansion valve has been proposed in which the stop valve and the expansion valve are integrated with each other (see e.g. Japanese Unexamined Patent Publication No. 11-182983 (FIG. 2)).
In the solenoid valve-equipped expansion valve of this kind, the integration of the stop valve and the expansion valve is a mere combination thereof in which the function of the stop valve and that of the expansion valve are independent of each other. On the other hand, a solenoid valve-equipped expansion valve has been proposed in which a valve element of the stop valve is configured to be commonly used as a valve element of the expansion valve, thereby making the valve structure compact in size (see e.g. Japanese Unexamined Patent Publication No. 11-304298 (FIG. 1 to FIG. 4)).
However, the above solenoid valve-equipped expansion valve in which the stop valve and the expansion valve have a common valve element is configured to be pilot-operated, which brings about the problem of complicated construction of the valve.